Vacuum cleaner



y 1943- G. E. LOFGREN 2,325,188

VACUUM CLEANER Filed Dec. 6, 1940 i751. as

INVENTQR.

Patented July 27 1943 Gustaf Einar Lofgren,

Riverside, Conn., assignor to Electrolu-x Corporation, New York, N. Y., a corporation of Delaware Application December 6, 1940, Serial No. 368,825 6 Claims. (Cl. 183-37) My invention relates to vacuum cleaners and more particularl to vacuum cleaners of the type which are pulled around on the floor by a. flexible hose.

In vacuum cleaners of this type, a dust separating member, such as a dust bag, is provided inside the unit, which also houses a, motor-driven multi-stage fan. The unit has a removable cover through which the dust bag may be removed. The dust in the bag is periodically emptied from the bag and the bag replaced in the unit. Very fine dust particles tend to clog up the pores of the dust bag after the cleaner has been used for a considerable time, and thus reduce the efficiency of the vacuum cleaner. A thorough shaking of the dust bag when the bag is emptied will prolong the efiicient use of the dust bag. However, unless the dust bag is thoroughly cleaned. or replaced by a new one, it is impossible to prevent a gradual reduction in eificiency of the vacuum cleaner.

Dust bags made of cloth are relatively expensive, especially when a finely woven cloth material is used inorder to provide an efllcient dust separator, and so it is not practical to frequently replace the dust bag by a new one. It has often been considered desirable to use a cheap material for forming-a dust bag, such as a coarsely woven cloth, or paper. A coarsely woven cloth is not satisfactory as dust bag material because it permits a large portion of the dust entering the vacuum cleaner to pas through it. Paper may be used but it is not satisfactory as a dust bag for a vacuum cleaner because either it does not have a sufilciently high tensile strength, or if a paper is used that has a' relatively high tensile strength, it is unsatisfactory because it also has a very high resistance to air flow through it.

An object of my invention is to provide an improved Vacuum cleaner with a dust bag that may be thrown away when it becomes too full of dirt for further use and replaced by a new one.

Another object of my invention is to provide a vacuum cleaner with means for readily determining when it is necessary to remove the dust bag and replace it.

What I consider to be novel and my invention may be better understood by reference to the following specification and appended claims when considered in connection with the accompanying drawing, in which Fig. 1 is a side view of my improved vacuum cleaner broken away in part to show the fan and the dust separator;

Fig. 2 is an enlarged detailed view of the inlet end of the vacuum cleaner unit; and

Fig. 3 is an enlarged top view of the inlet end of the vacuum cleaner showing the indicator in the front cover.

Referring to the drawing, Ill indicates a vacuum cleaner casing housing a multi-stage fan II driven by an electric motor, not shown, and a dust separating member including a cloth bag I2 and a paper dust bag I3 within it. The fan II produces a flow of air from left to'right 0f the casing I 0, as shown in Fig. 1, drawing air in through a flexible hose I4 connected in the inlet opening of a front cover I5. The air is discharged from an opening IS in a rear housing I! secured to the casing I0. Cloth ba I2 engages a perforated plate I8 which is urged toward the left of the casing II], as shown in Fig. 1, by means of a compression spring I9.

When the fan I I is operating, air enters casing II! with entrained dirt removed from a rug or other surface being cleaned. Most of this dirt is separated from the air as it passes through the paper bag I3. Some of the finer dirt, however, may pass through the bag I3 and enter the bag I2. This fine dust. tends to clog up the bag I2, and increase the pressure lost in forcing the air through the bag as a result of an increased resistance to air flow through it. Since the suction produced by the fan II is a maximum at the.

entrance to the fan and is reduced progressively toward the suction nozzle. by the resistance of the various parts to air flow, this increased resistance to the air flow through the cloth bag I2 tends to raise the pressure within it, and likewise the pressure difference on the two sides of the bag. This creates a greater pressure per square inch on the left side of plate I8, due tothe greater pressure tending to expand the cloth dust bag I2 as the resistance rises. This force tends to move the plate I8 to the right against the resistance of the spring I9. As plate I8 goes to the right, it moves an arm 20 connected to it at one end against the bias of a spring 2|. Movement of the arm 20 carries with it an integrally connected indicator 22 which may be viewed through a window 23. Thus, if cloth bag I2 becomes clogged, the indicator 22 shows the condition of the bag. Means may bemarked on the indicator 22 to show when it is necessary to actually remove the cloth bag l2 from the casing l and empty the fine dust collected in it. The

paper dust bag I3 must be removed even moreoi'ten than the cloth bag l2 because it retains the major portion of the dust separated from the air in its passage through casing Hi. If the paper dust bag l3 clogs up it will also tend to expand the cloth bag 12 and move the plate l8 to the right. However, if the paper dust bag l3 alone is clogged, this condition can be discovered by examining the indicator provided in the cover, as explained below. In addition, if the paper dust bag l3 clogs up, the increase in the pressure drop through it tends to expand the bag [3 and may produce such a large force that it may tear the paper. Therefore, it is highly desirable to remove the paper dust bag i3 befo--e so great a force is produced that it destroys the bag.

The paper dust bag l3, as best indicated in Fig. 2, is secured to an extension 25 formed integrally withthe cover 5. The open end of the dust bag l3 fits over extension 24 and is secured thereto by means of a binding 25 seated in a groove 26 in extension 24. Bust bag I3 is removable from casing ID with cover l and may be separated from cover l5 by removing binding 25. An indicator 21 is secured directly to the cover l5. Indicator 21 is provided with a two-part housing including a top 28 and a bottom 29. A flexible diaphragm 30 is secured within the indicator 21 by means of an outwardly extending portion 3! extending between the two parts 28 and 29. The two parts 28 and 29 and the diaphragm 30 are secured together by means of rivets 32. A rod or arm 33 is secured to the center of diaphragm 30 at its inner end and is connected to a target 34 at its outer end. Arm 33 and target 34 are urged toward the left, as shown in Fig. 2, by means of a compression spring 35. The left side of the diaphragm 30 is subjected to the pressure within the inside of the: paper dust bag l3 through two openings 36 provided in the top 28. The right side of diaphragm 30 is subjected to the pressure on the outside of the paper dust bag I3 through an opening 31 which extends through the bottom part 29 and the extension 24.

When the dust bag I3 is new, the pressure drop through it is very small and so the difierence in pressure on the two sides of the diaphragm 30 will be small. In this condition, the spring 35 will bias the arm 34 to an extreme position to 1. A vacuum cleaner including a casing, a motor-fan unit mounted within said casing for prothe left. If the dust bag 13 becomes clogged, the

resistance to air fiow through it increases so the dlflerence in the pressure on the two sides correspondingly increases. With the increased difference in pressure on the two sides of the diaphragm 30, it will move the arm 33 to the right as shown in Fig. 2. When the arm 33 is moved to an extreme position to the right, it will indicate by means of target 34 through the window 38 by an appropriate mark thereon that it is necessary to remove and replace the dust bag i3.

In Fig. 3, the indicator is in a position indicat ing the necessity of replacing the paper dust bag l3 by a new dust bag. The indicator for the cloth bag 12 may be omitted if desired and the general indication of the operation of the cleaner relied upon to show the desirability of cleaning it.

It is to be understood that while a preferred form of the invention is illustrated, the

ducing a flow of air therethrough, a cover having an inlet opening secured to said casing, an extension on said cover extending within said casing, a paper dust bag secured to said extension and extending within said casing, a ring clamped between the end of the casing and said cover and having a flange extending within said casing, a cloth bag secured to the flange of said ring and surrounding and reenforcing said paper dust'bag.

and an indicator mounted on said cover communicating directly with the interior of the paper dust bag and communicating through an opening in the extension with the exterior of the paper dust bag.

2. In a vacuum cleaner, means for separating entrained dirt from air passing therethrough comprising a first filter bag of a material which is incapable of withstanding the full air pressure differential produced by the vacuum cleaner when the pores of said filter are clogged, and a second filter bag of flexible material surrounding said first bag and of such size as to support it against the vacuum cleaner air pressure; means indicating movement of the second bag, and means responsive to the air pressure on the inside of the first bag and to the air pressure in the space between the bag's for indicating the resistance to air flow offered by the first bag, said last mentioned means comprising means to space apart the mouths of said bags over a sufficient distance to provide access to the'space between the bags, and means to communicate the pressure from the space between the mouths to said indicating means.

3. In a vacuum cleaner, means for separating entrained dirt from air passing therethrough comprising a first filter bag of a paper material which is incapable of withstanding the full air pressure differential produced by the vacuum cleaner when the pores of said filter are clogged, and a second filter bag of fiexible cloth material surrounding said first bag and of such size as to support it against the vacuum cleaner air pressure; means indicating movement of the second bag, and means responsive to the air pressure on the inside of the first bag and to the air pressure in the space between the bags for indicating the resistance to air fiow offered by the first bag, said last mentioned means comprising means to space apart the mouths of said bags over a sufilcient distance to provide access to the space between the bags and means to communicate the pressure from the space between the mouths to said indicating means.

4. In a vacuum cleaner, a first filter bag, a second filter bag surrounding the first bag, means for indicating the resistance to air flow ofiered by the first bag responsive to the air pressure in the space between said bags and to the air pressure in the space on the inside of said first bag, and means responsive to the expansion invention having an inlet opening presented to the air inlet of the casing, means for indicating the resistance to passage of air through the outer bag to thereby determine the clogged condition of the latter, said indicating means also operating in response to variations in pressure in the inner bag, and means for indicating resistance to passage of air through the inner bag, said latter means being constructed and arranged to operate even though the pores of the outer bag are open for substantial unrestricted flow of air therethrough to thereby indicate in conjunction with said firstnamed indicating means when the inner bag alone becomes clogged.

6. In a vacuum cleaner, a casing having an air inlet and an air outlet and means for creating a flow of air through the casing from said inlet to and through the outlet, an inner porous filter bag, an outer porous filter bag surrounding and reinforcing the inner bag, said inner bag having an' inlet opening presented to the air inlet oi the casing, multiple gauge means -for indicating the clogged condition of said bags, means for actuating a portion of said gauge means in accordance with resistance encountered to passage of air through both bags, and means for actuating another portion of said gauge means in accordance with the resistance encountered to passage of air through the innerbag, said latter means being constructed and arranged to operate even though the pores of the outer bag are open for substantial unrestricted flow of air therethrough.

GUSTAF EINAR LOFGREN. 

